The Shimano GRX BL-RX825 is a dedicated brake-only lever built for Di2 gravel drivetrains, paired here with the BR-RX820 flat mount hydraulic disc brake caliper for the rear. Together they deliver precise, reliable stopping power for mixed-terrain and endurance gravel riding — purpose-built for riders running a wireless Di2 shifting setup who want class-leading ergonomics and modulation.

Highlights

• GRX gravel ergonomics: Raised hoods with a ribbed surface and anti-slip brake lever blade provide secure grip and control across rough terrain and in variable conditions.
• Flared bar optimised: The hood profile is shaped specifically for flared drop handlebars, keeping hand position natural whether you're on the hoods, drops, or in the flare.
• Di2 integration: The BL-RX825-L is a brake-only lever designed to pair with the right-hand ST-RX825 Di2 dual control lever, allowing a clean, hose-only cable run on the left side.
• Reach adjust: Tool-adjustable lever reach accommodates a range of hand sizes and personal preferences.
• Wide pad clearance: The BR-RX820 caliper features 10% wider pad clearance compared to previous GRX calipers, reducing brake noise and drag.
• Easy maintenance: Shimano's One-Way Bleeding system keeps air out and simplifies servicing in the field or workshop.
• Finned resin pads: Includes L05A finned resin compound pads for improved heat dissipation during long descents.

Lever & Caliper Detail

The BL-RX825-L uses hydraulic actuation with Shimano mineral oil and a SM-BH90-JK-SS hose. Its lightweight construction — approximately 188 g for the lever — keeps unsprung weight low. The lever body is carbon fibre reinforced plastic (CFRP), with a glass fibre reinforced plastic (GFRP) function button and an aluminium brake lever blade, delivering strength without excess weight. The clamp diameter accommodates 23.8–24.2 mm handlebars.

The BR-RX820 caliper uses a 2-piston flat mount design with aluminium construction and resin pistons. Its low-profile flat mount architecture integrates neatly into modern gravel framesets without adapters for rear use, and it is quieter and easier to bleed than previous-generation GRX calipers.

Compatibility & Fit

The BL-RX825-L is compatible with all Shimano 12-speed wireless Di2 systems including GRX, Dura-Ace, Ultegra, and 105 Di2. Recommended hose: SM-BH90-JK-SS. Recommended rotors: SM-RT64, SM-RT70, SM-RT800. The BR-RX820 caliper uses a flat mount rear interface. This set is sold as a left-hand lever with rear caliper — consistent with Australian brake convention (left lever = rear brake). Note: a rotor is not included.